1. Field of the Invention
The invention relates to non-contact methods of examining parameters of external actions on various media or objects. Such an action could be of various types, e.g., physical (pressure, heating, electric or magnetic field etc.), chemical (action of various chemical substances and associated reactions: binding, replacement, catalysis etc.), biological (action of microorganisms or viruses on a nutrient medium). The invention could be used in scientific research, technology and environmental monitoring.
2. Information Disclosure Statement
The known method to measure parameters of an external action on a medium or an object, which is most closely analogous to the proposed one, comprises specification of reference relationships between a response signal and the external action on a sensitive medium, action by electromagnetic radiation on one of the sides of a structure made of a metal film deposited on a substrate, said medium being placed from the side of the metal film with respect to said structure, excitation of a surface electromagnetic wave (SEW) in the metal film, and generation of a response signal from said structure, one judging the parameters measured from comparison of said signal with the reference relationships [B.Moslehi, M. W. Foster and P. Harvey, "Optical magnetic and electric field sensors based on surface plasmon polariton resonant coupling". Electron. Lett., 27 (1991) 951-953]. The value of the measured parameter of an external action is obtained from recording the position of the resonance maximum of a SEW excitation efficiency or relative value of the SEW excitation efficiency within the slope of the resonance.
The associated apparatus for measuring parameters of an external action on medium or an object, which is most closely analogous to the proposed one, comprises an electromagnetic radiation source, a solid structure including a metal film serving for exciting a SEW in it, deposited on a substrate, and an information processing unit [B.Moslehi, M. W.Foster and P. Harvey].
The advantage of the mentioned method and the apparatus is a non-contact character of measurement accompanied with high accuracy. This enables one to solve a wide range of problems for examining various types of an external action on various media or objects. However, the response signal is here a purely optical signal resulting from changing parameters of a radiation beam reflected from the metal film under conditions of resonant SEW excitation in the film. To record a response signal associated with the reflected radiation beam, there is a need for a registration channel including an optical arrangement with a photodetector unit. This makes an overall device rather cumbersome, complicated and expensive and restricts the device's capabilities (particularly, its accuracy and its resolution limit), especially, when using an adjustable optical arrangement. Using a fixed one limits the dynamic range of measurements and the area of possible applications. These are significant intrinsic drawbacks of the mentioned method and the associated apparatus.